DESCRIPTION(provided by applicant): At Origin Therapeutics we have derived chicken embryonic stem cells (cES) that can be maintained in culture for extended periods of time and contribute extensively to the somatic tissues in chimeras and at low levels to the germline. Origin's goal is to use these cES cells to create transgenic chickens producing clinically relevant pharmaceutical proteins in their eggs. Origin has established routine procedures for stable transfection of ES cells with constructs up to 160 kb and has produced chimeras with ES cells carrying a 45 kb transgene that encodes the production of the heavy and light chain components of a human monoclonal antibody. This monoclonal antibody is expressed exclusively in the tubular gland cells of the oviduct and is exported into egg white. For optimal production of proteins fully transgenic chickens are required necessitating robust germline transmission. In recent years differentiated somatic cells have been derived from human and murine ES cells. Most recently oocytes and sperm have also been derived from mouse ES cells. In the chicken PGCs migrate to the gonads through the vasculature. Exogenous PGCs, when injected at the appropriate time, can substantially colonize the germline of recipient embryos. To obtain robust levels of germline transmission this application proposes to derive PGCs from embryonic stem cells and to colonize the gonad with in vitro derived PGCs. [unreadable] [unreadable]